The appliers of political science had no doubt about it. At universities across America, they fed all the relevant data about the economy, wealth, jobs and crime into their computers - and produced an overwhelming verdict. Hail President Gore! An open-and-shut case. But now the computers themselves are shutting down.

The presidential race rates as high summer horror. The nation is on heatwave holiday, drifting between barbecue and beach, manifestly uninterested in politics. TV viewing figures for the Republicans in Philadelphia were sharply down on 1996: the big turn-off proceeds exponentially over decades.

Yet modern history also says that the candidate who leads the polls on Labour Day weekend at the start of September is the candidate who wins in November. Only Ronald Reagan, 20 years ago, bucked that law - and whatever else Al Gore is, he ain't no Ronald Reagan.

The Vice-President comes to Los Angeles this week trailing a cautiously triumphant George W. Bush on every one of those polls, usually by more than 10 points. The convention is his only realistic chance of getting back into contention. Either he begins to transform the way America sees him - warm, not chilly; interesting, not boring; human, not policy wonkish; Al, not Bill - or he will be the pre-ordained loser.

No easy brief. I have, as it happens, met Gore twice. One time (an interview) he couldn't have been more superciliously brusque. Southern charm? Forget it. He could hardly bother to move his lips. And the other time (in Boston this spring) he kept an international conference waiting for half an hour while he slotted in unscheduled TV appearances in the back lobby. His record for failing to win friends is richly deserved.

Is Clinton-Gore the problem, as the Republicans would have us believe? Are 'dignity' and 'honour' the buzz words for success? The funniest thing of all in the polls is the way that the supposedly reviled Clinton, now peddling New Penitence like a stomach powder, still coasts along with 60 per cent approval ratings, while the man who didn't touch Monica Lewinsky - or fib about it - is 20 or so points behind that. Gore has an effusively loving wife, an adoring family, and Southern morality to spare: but, for the moment, he is also the issue. His policy platform isn't popular: but he is less popular still.

So to the Los Angeles personality transplant ward. Al has been taking the pre-med tablets already, voyaging relentlessly to hometown meetings in Carthage, Tennessee, with his new friend Joe Lieberman and three dozen camera crews to meet grey-haired women who remember him as a lovable guy. His collar is ritually unbuttoned these days, jacket cast aside. He's regular and relaxed and (not for the first time) re-made.

How will it play in LA? The selection of Senator Lieberman as his running mate may not be enthusing the big donors of Hollywood, but otherwise it went down well. Lieberman arrives on the main screen as a 'moderate' beloved on both sides of the Senate (a word reserved for Mr Conservative in-betweens). Most of the attention may have concentrated on his Orthodox Jewry - and the blonde second wife whose parents escaped a Nazi concentration camp - but he has one attribute beyond mere history. He's a politician who answers the question: a pearl beyond media price.

Ask Senator Joey (as his wife calls him, to winces off) why he doesn't follow the Gore line on education vouchers - or, more difficult - whether he intends to run for the Senate as well as the vice-presidency, and he'll give you a straightforward, thoughtfully clear response. The human being bit comes naturally.

This is not altogether good news for Gore. Lieberman is on the ticket because his was the first sombre voice to speak out against sex in the Oval Office. He's a formal break with the sleaze of the past. But he also possesses the vital attribute his master lacks. He couldn't be wooden if he tried.

It is one of the great curiosities of this election that both main candidates now have putative Vice-Presidents who, on any normal count, are better - more knowledgeable, more sentient, less mechanical - than they are themselves. The Veeps look better than the Prezzas. And neither of them, disasters aside, has any real chance of being President themselves. Time and age are against them.

Gore is the Democratic contender now because he wasn't as good as Bill Clinton then. He inherited rather than won the nomination. He has, thus far, lacked any clear strategy - trapped between attacking the Republicans and defending a dying administration.

Now he has to stand in his own right. He has to deliver the assets the computers have stored. Now he has to win a few hearts - or, at the least, show that he has one.